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LooPING IN MBGHANISM FOR TELEPHONE SWITCH BOARDS.

Patented June 12,1883.

MAIN LINE UFERATUR.

N. PETERS. muuwgmpw. wmxww. D. c.

UNITED STATES PATENT OFFICE.

EUGENE n. WILSON, orv WORCESTER, MASSACHUSETTS, AsSIeNoE or ONE- nALE To EDWIN r. CARPENTER., oEsAME PLACE.

LjOOPlNG-IN MECHANISMFOR TELEPHONE SWlTCHeBOARDg.

5 SPECIFICATION forming part of Letters Patent No. 279,471, dated June 12, 1883, Application :nea Marh 1, Issa. (No maar.)

T all whom it may concern:

Be it known that I, EUGENE M. XVILsoN, of Worcester, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Looping-III Mechanism for Telephone Switch-Boards; and

I declare the following to be a description of mysaid invention sufficiently full, clear, and

exact to enable others skilled in the art to Io which it appertains to make and use the same,

reference being had to the accompanying drawings, which form a part of this specification.

rlhe object of my present inventionis to provide an efficient, simple, and convenient at- I5 tachment for use in connection with telephone V`switch-boards for looping in the attendants telephone and transmitter, or apparatus employed at central offices and telephonie exchanges to enable the operator to listen to and 2o answer calls and messages, and to afford facilities for the Inore perfect and satisfactory government of thelines with less labor and inconvenience for the attendants and for the execu- I tion of changes in a more expeditious manner than with apparatus heretofore in use. These objects I attain -by mechanism organized for operation. substantially as illustrated and described, the particular subject-matter claimed being hereinafter' definitely specified.

In the drawings, Figure l is atransverse sectional view of my improved looping-in apparatus, with diagram showing the arrangement ofthe connecting-lines, &c. Fig. 2 is a part front, part longitudinal sectional, view of .the 3 5 same. Fig. 3`-is a side view ot' the reversible connector or commutator-plug. Fig. 4 is a top view ofthe same. Fig. 5 is abottom view of the same. Fig. 6 is a cross-section of the plug at line w fw, and Fig. 7 is a cross-section 4o of the plug at line :c c".

My improved loopiIIg-in mechanism is ap,

plicable to any of the ordinary s\\'itell.-boa1'tls in use for telephonie exchanges.

It comprises series of metallic springs corresponding with the several Inain lines, ar-

ranged and coimected with the circuit-wires or conductors in the order substantially as illus- Y lustrated, said springs being adapted for closing or breaking the circuits or for changing 5o the direction of the electric currents by the insertion and manipulation of a plug or pointbar provided with'a signaling-key and having contact-plates arranged and connected in the peculiar manner set forth, to effect the transposition, of the circuits as required, said 'plug being revoluble within the bench or frame without requiring its removal, andthe several plate-connections being entirely inclosed or embedded within the plug, thus making it 'complete within itself and avoiding the use of 6o appendant cords or wires that interfere with the free use of the plug. The several. parts of the apparatus may be arranged as follows: A indicates the supporting bench or frame, formed of wood and placed along the front of theswitch-board, or at any convenient position. The front piece, a, ofthe. bench is perforated with a row of circular openings or tubes corresponding to the several ,main lines, and numbered l., 2, 3,4, &c., ac- 7o cordingly as the several lines are designated.

t B B indicate pairs of fiat` metal springs secured to the back piece, c, of the frame, and extending forward with their front ends arranged to lie in contact with each other when vin, normal position, but curved so as to permit the insertion between them of the plug C. To the springs B are connected the main lines or subscribeNs wires D, and to the springs B/ are connected the lines or wires D', running to 8o the switch-board and ground, or vice versa; K Forward ofthe line-springs B B are placed the instrument-springs or loop-connectors E E, respectivelv supported on the top and bot- .toni pieces, a? c, ofthe bench A. All of the upper tier of springs, E, are `joined to a conductor, c, running to the end of the bench A, and 'all of the lower tier of springs, E', are in p similar manner joined to a conductor, c, also running to the end ofthe bench; and to these 9o con ductors c c, I connect, respectively, the ends of 4the wire or loop E2, that passes through the The springs E and E are preferably made so' that their loose ends will take a bearing on the frame A when the plug C is thrust between them, thus insuring their firm pressure against the surface ofthe plug or contactplates iixed thereon. 'The springsV E and F] operators telephone F and transmitter F.

are so adjusted that they will not strike against Ioo each other when the plug is withdrawn. rlhus the loop-circuit El vis broken, or cut out from the general circuits, except at such position and at such times as the plug C is between some pair of the springs E E.

Forward of the instrument-springs E, I arrange another row of springs, G, supported on the front piece, a, of the frame and severally joined to the conductor g, which extends to the end'of the bench and connects with the line or wire H, that leads from the elect-ricalA battery H, magneto-generator, or other apparatus employed for developing or supplying the electric force.

The several series ot' springs B B E E G are arranged in relation to the tubes or openings l 2 3 4, ttc., in such manner that when the plug C is inserted in one of said openings all of the springs in that series, or corresponding with a particular main-line wire, will take independent and uniform bearing upon the plug, the pair oiline-springs B B being separated from each other in the manner illustrated in Fig. 1.

The connector or comniutatorplug C is made as illustrated in Figs. 3 to 7, inclusive. The portion which enters the front piece, a, of the bench is of cylindrical form, of a proper diameter to iit the openings or tubes, so that it will be properly supported therein, while it is sufficiently free to be easily revolved within the tube or opening without removing it therefrom. The adaptation ot' the plug for rotation without withdrawal is a feature of myinvention. The body of the plug is made i'rom suitable insulating material, and `the inner portion is provided with conducting-metal contact-plates, as shown-viz., on its upper side the three plates I) c d and on its lower side the two plates f and d. The outer portion ot' the plug is provided with a metallic spring-key, fi, an anvil, m, for the key to strike upon, and a back contact, l, i'or the key to strike when elevated. The contact-plate b is connected to the spring-key by awire, b. The contact-plate c is connected with the back contact, Z, bya wire, c; and the contact-plates d d are connected to each other through the plug, and to the anvil m by the wircon. All of these connections are inclosed or embedded within the insulating-body oi' the plug, as indicated by the dotted lines in Figs. 3, 4, and 5, so that the plug is complete in itself, and has no attached cords or wires to interfere with its free manipulation.

The operation of my improved apparatus is as follows: A call-current from the subscriber coming in on one of the main lines l) passes through the springs B B the ends oi' which rest against each other when the plug is not in) and operates the usual call-signal devices (not shown) ofthe switch-board. The plugC is then inserted by the attendant or operator into the opening of the bench corresponding with the line signaled, thereby separating the springs B B and establishing the circuit through the operators instrumentF F by way of the contact-plate b', wire b. key z', back contact, Z, connections c', contact-plate c, the looping-in spring E, conductor e, and line Ff, thence back through conductor c, spring E', contactplate f, spring B, and line D to the switchboard, on which the operator, after ascertaining from the person-calling the particular station desired, makes the proper adjustments 'for connecting the designated main lines D in the usual .mannen There are two methods cmployed in practice for answering calls from the central oice. One is for the subscriber to immediately take his telephone and listen for the voice ofthe central-office attendant. rllhe other is for the subscriber to await an answering ring upon his bell. ln the iirst method, the operator, after inserting the plug C between .the set ot' springs, simply speaks to the subscriber through the transmitter F. ln the second method, after inserting the plug C, the operator depresses the key A, thereby estab- `lishing a circuit from the ground through the generator H, line H, conductorl g, spring G, contact-plates (l fl, wire' m, anvil m, key f,

`wire b, contact-plate b, spring B, and line l) to the subscribers instrument, for ringing his bell and giving h im the expected answer-signal, on receipt ot' which he places his telephone to his ear, and the operator lets up the key ri and converses with him for ascertaining his wishes regarding the eonnecti on desired. During the time the key i is in contact with the anvil m the circuit through the operator7 s instrument F F is broken. After the proper line-connections have been made on the switchboard, the operator revolves the plug C without withdrawing it from the opening, (being enabled so to do by reason ot' its cylindrical form,) and the position of the plug being then reversed, (see dotted lines, Figs. land 2,) the operator can, by depression ol" thekey fi, send the signal-current through the switch-board and out upon the connected line for calling up the second subscriber by a bell-call rung in a manner similar to the bell-call answer to the first subscriber. The operator can thus send signals alternately to one and the other of said subscribers by simply revolving the plug C to reverse its position without withdrawing it i'rom between the pairs oi" springs, and depressing the key li, as required, the operation being very quickly and easily performed. After` the subscribers have been. properly placed in communication, the plug C can be withdrawn, letting the springs B B come together, thereby disconnecting the loop E, or circuit through the operator7 s instrument, and establishing the circuit direct through the springs B B and lines D. The operator can in this manner instantaneously loop-in to any of the line l) by inserting the plug C at the position of the bench corresponding with the/ line desired. l 10o It will be observed that the plug C is supported by the front board, (l, so that it enters IOO IIO

direct between the springs, and there can be no side action tending to strain 'and weaken the springs, thereby impairing their efficiency .of contact with the several contact-plates of l made in a continuous piece extending from one end of the bench to the other, in lieu of being independent springs connected by the Wire-conductors, as herein shown, and said continuous piece could be slit or partiallyl separated'betwecn the several sections, if preferred. v

What I claim as of my invention, and desire to secure by Letters Patent, is-

1. An operators hand-plug for loopingin and making signal-connections on telephonelines, formed complete Within itself, with a signal-key and series of interconnected contact-plates free from attached cords or dependent conductors, and having its insertible portion made of cylindrical forln or adapted to be reversed, substantially as and for the purposes set forth. 1

2. The plug provided with signaling-,key fi, back contact, l,- anvil m, and contact-plates b c d df, severally connected in the manner shown by Wires or conductors embedded or inclosed Within the body of the plug,` substantially as and forthe purpose set fort 3. In a telephone-exchange apparatus, the combination of" a series of independent springs or contact-bearers severally connected with the main and switch-board lines, a pair or series of loopingfin springs or contact-bearers 35 arranged adjacent thereto and connected with the operators instrument, a generator contact or spring, and an interchanging commutatorplug provided with a signaling-key, back contact, and anvil, severally connected Within 4o said plug to a series of contact-plates that sev erally take bearing against the said springs When the plug is inserted between them, for looping-in or establishing the circuit through the o Jerators instrument and the transmis-` sion of signals, substantially as liereinbefore set forth.

4. The frame or bench A, provided with tubes or circular openings, the springs E E G, arranged along saidy bench in rear of said 5o openings and respectively connected with the instrument-loop E2 and generator-line H, the line-springs B B, respectively connecting the main lines D and switch-board lines D', and the revoluble plug C, provided with con- 5 5 tact-plates, signaling devices, and connectingconductors, substantially as described.

W'itness my hand this 21st day of February, A. D. 1882.

EUGENE M. TILSONL Witnesses:

CHAs. H. BURLEIGH, JAMES MonToN. 

